Archive for January, 2009

The weekend is going to be sunny for the most part and a warming trend will set in making Sunday much warmer than Saturday. A southerly wind will bring up the milder air. On Saturday, temperatures will be hard pressed to reach 40 degrees. On Sunday, 60 degrees is within reach in some inland spots, especially in NC. Then, all eyes turn to a low pressure area that will be taking shape along the Gulf Coast. This low is going to intensify as it moves rapidly northeastward late Monday and Tuesday. There are still questions regarding the track of this system. For us here in Hampton Roads, the precipitation type will most likely be in the form of rain, with maybe some snow or flurries at the end of the event. However, for folks to our north, the precipitation type is very questionable. If this takes a certain track, heavy snow could fall in DC and points north and east. If you are traveling early next week, please monitor this system closely. I’ll have a full update on this system in my Sunday morning post.

A cold front moved through the Mid-Atlantic region on Saturday dropping temperatures and shifting our winds to the north. On Sunday, it will be a struggle to get out of the thirties. Then, things get a little interesting. A strong jet stream is expected to develop over our part of the country on Monday and it will be a mostly west to east (or zonal) flow. This will be the dividing line between the arctic air to the north and the relatively milder air to the south. Moisture will also be lurking well to our south through the week. Disturbances are expected to move east along this fast flowing jet stream with each one having the potentail to cause some precipitation. The questions are 1) What type of precipitation will fall?, 2) Where will the main area of precipiation be? 3) How heavy will the precipitation be? 4) When will the precipitation fall? The first chance of precipitation is late Sunday night and early Monday. It appears at the time of this writing that most of the precipitation will fall offshore. Anything that falls here locally should be fairly light. The forecasting challenges will grow with the next system as it will be a stronger system and pass much closer to the region. My thinking is that the precipitation will fall predominately in the liquid form here in Hampton Roads, with only a brief period of frozen precipitation (snow/sleet) possible. There is a potential for a “Miller B” type system forming, so stay tuned. Further north and west, there is a good chance of accumulating snow/sleet this week, so if you are traveling check the forecast ahead of time. So, the bottome line for the snow lovers here in Hampton Roads is that I don’t think that this pattern is ideal for snow here locally. Had this arctic air been a little further south here in the east, we would have had a better chance of snow. However, any small shift in the pattern could bring snow to this area but I don’t think it will happen this week. If you want to see snow, just go up to the Northern Mid-Atlantic region and you should see it this week.

Southwesterly winds will bring in milder air Thursday and especially on Friday. Temperatures should top out in the upper 50’s on Friday. The weekend looks okay but a shower cannot be ruled out early Saturday. Arctic air is once again on the move in northern Canada and we may see a piece of that air mass early next week. There also may be a frontal system approaching bringing some moisture to our region at the same time, so stay tuned. After the forecasting fiasco earlier this week, folks aren’t going to believe it when the weathermen predict snow for Hampton Roads, but trust me, errors of this magnitude are rare. Nearly every model had SE VA getting at least some snow. My thinking is that meteorlogists should use their judgement and not just go by the models. As I stated in my previous post, the dry air won out but the next time, that may not be the case. I’ll have a full post on Saturday.

For the folks in Hampton Roads, everyone is asking “what happened to the snow that was predicted here today?” To simplify the answer, the dry air won out over the moisture. In addition, the wind direction didn’t help produce snow by bringing in moisture from the ocean. Overall, the low pressure area was just too far away. Why didn’t forecasters see that? I’m not sure. I do know that a forecaster did think that we would be missed by the snow today, but he is not located here in Hampton Roads. It is very hard to predict snow here locally as many things have to come together to produce snow. Please read my weather fact that discusses this issue in detail for Hampton Roads.

As the headline states, the NWS has issued a Winter Storm Warning for Southside Hampton Roads and NE NC on Tuesday. Why? Well, a low pressure area is expected to develop to our south and west later on Monday. As this low moves to our south on Tuesday, it is expected to intensify as it pulls in colder air. This low should produce a swath of significant snowfall and pinpointing exactly where that will be is quite difficult at this time. The current thinking is that the heaviest snow will fall from the Raleigh area E-NE to Elizabeth City, NC. A slight shift in the low’s track and everything changes. Based on the predictions that I’ve seen, the average is about 2-4 inches in Hampton Roads with more to the south and west. This will be the last in a series of disturbances that have been diving southeastward into the Mid-Atlantic States. One disturbance that moved through on Sunday brought about 0.40 inches of rain to my backyard. The combination of the damp ground and light winds caused some dense fog in areas early Monday morning. Some locations reported black ice on roadways in our northern and western areas. The fog will lift today and there is a chance of a shower or two. The wind shifts from the SW to the N overnight and that is what will bring in the chillier air. As the low pressure area approaches the area on Tuesday, steadier snow is expected to develop. Temperatures are expected to be cold enough to support snow. Things quiet down on Wednesday and temperatures should slowly moderate. Please drive safe and remember to leave plenty of room between your vehicle and the one in front of you.